IDENTIFICATION_INFORMATION

Citation: Citation_Information: Originator: Brian Donahue, Univ. of S. Florida
Publication_Date: 20020105
Title: Simrad EM-120 Multibeam Bathymetry Grid, Tutuila Flanks,
American Samoa
Edition: 1
Geospatial_Data_Presentation_Form: Map
Publication_Information: Publication_Place: Tutuila, American Samoa
Publisher: Fagatele Bay National Marine Sanctuary Office
Other_Citation_Details:article Online_Linkage:HTTP://dusk.geo.orst.edu/djl/samoa Larger_Work_Citation: Citation_Information: Originator: University of South Florida
Publication_Date: same as above
Title: same as above
Publication_Information: Publication_Place: same as above
Publisher: same as above
Online_Linkage: same as above
Description: Abstract:
This is bathymetric grid from data collected with the Kongsberg Simrad
EM 120 systems aboard the R/V Revelle, Leg 10 of the Drift Expedition
(Cruise DRFT10RR), Pago Pago to Pago Pago, March 7-8, 2002 (Chief Scientist, David Naar,
NSF/NOAA funding to Naar and Wright). This one day cruise (along with
other multibeam data mined from the archives) enabled complete coverage of
the mid to deeper water flanks of Tutuila. The entire north flank of the island and
some multibeam data gaps along the southern flank have been mapped, revealing
some new volcanic cones (at least 6 off the northern flank), as well as the
shape (and more accurate location) of charted (but unmapped) banks.

The data were post-processed by Brian Donahue using the Kongsberg Simrad
Postprocessing software package Neptune. The geodetic parameters that were
used are as follows:

Datum: WGS84
Half axis: 6378137.0000000
Flattening: 1/298.25722356300
Coordinate system: Latitude/Longitude (Decimal)
The data were processed at various scales. The end of the name in the
fledermaus files designates the grid cell size for each image. For example the
Taema Bank folder contains taema_bank_1m, this means that the grid cell size
for this image is 1 meter. Bathymetric post-processing includes: tidal correction
followed by analysis of the noise level and standard deviation. Correcting for tidal
variation was completed by using verified data from the NOAA tide station at
Pago Pago harbor (1770000) Following the tide correction, data that exceeded
the second standard deviation of surrounding data and those that exceeded two
percent of the noise limit were flagged as not valid. The remaining data were
exported as XYZ data containing all the points that were valid after post-
processing. The XYZ data was read into IVS Fledermaus software for
presentation and analysis purposes. From the Fledermaus software the data was
then exported into an acceptable format for ArcView. The ArcView format could
then be read into Arc 8. After processing the raw, processed, and XYZ files were
compressed using WinZip and are archived at the University of South Florida's
College of Marine Science.

The data were processed at various scales. The end of the name in the
fledermaus files designates the grid cell size for each image. For example the
Taema Bank folder contains taema_bank_1m, this means that the grid cell size
for this image is 1 meter. Bathymetric post-processing includes: tidal correction
followed by analysis of the noise level and standard deviation. Correcting for tidal
variation was completed by using verified data from the NOAA tide station at
Pago Pago harbor (1770000) Following the tide correction, data that exceeded
the second standard deviation of surrounding data and those that exceeded two
percent of the noise limit were flagged as not valid. The remaining data were
exported as XYZ data containing all the points that were valid after post-
processing. The XYZ data was read into IVS Fledermaus software for
presentation and analysis purposes. From the Fledermaus software the data was
then exported into an acceptable format for ArcView. The ArcView format could
then be read into Arc 8. After processing the raw, processed, and XYZ files were
compressed using WinZip and are archived at the University of South Florida's
College of Marine Science.